Switch construction



S pt. 13, 1949. E. A. LINK 2,482,009

SWITCH CONSTRUCTION Original Filed June 2, 1944 9 Sheets-Sheet 1 mam arm/v 10/ INVENTOR. [mum 4 l/A/A Sept. 13, 1949. E. A. LINK SWITCH CONSTRUCTION 9 Sheets-Sheet 3 Original Filed June 2, 1944 IN VEN TOR. [DIM/V A ..///V/( Sept. 13, 1949. E. A. LINK 2,482,009

SWITCH CONSTRUCTION Original Filed June 2, 1944 9 Sheets-Sheet 4 INVENTOR. [um/v A [/NA Sept. 13, 1949. E. A. LINK 2,482,009

SWITCH CONSTRUCTION Original Filed June 2, 1944 9 Sheets-Sheet 5 INVENTOR. 7 [aw/VA lm A ATTO/F EV.

SWITCH CONSTRUCTION Original Filed June 2, 1944 9 Sheets- Sheet 6 Sept. 13, 1949.

Original Filed June 2, 1944 E. A. LINK SWITCH CONSTRUCTION 9 Sheets-Sheet 7 INVENTOR. fan/M04 [l/VA 'ZZZMKW Sept. 13, 1949. E. A. LINK SWITCH CONSTRUCTION 9 Sheets-Sheet 8 Original Filed June 2, 1944 INVEN TOR [ow/v A Z/A/A/ Sept. 13, 1949. E. A. LINK SWITCH CONSTRUCTION 9 Sheets-Sheet 9 Original Filed June 2, 1944 W U A @f Y, B

Patented Sept. 13, 1949 swrrcn CONSTRUCTION Edwin A. Link, Milwaukee, Wis., assignor to Line Material Company, Milwaukee, Wis., a corporation of Delaware Original application This invention relates to a switch construction.

In greater detail, this invention relates primarily to a switch construction of the circuit breaker type.

This application is a division of my copending application Serial No. 538,365, filed June 2, 1944, for Switch constructions.

Objects of this invention are to provide a circuit breaker which has a quick make and a quick break, which has condition responsive means of the trip type, which is so constructed that it releases the circuit breaker so that. the circuit breaker will open under predetermined conditions, and which is provided with a handle or other operating means for normally opening and closing the circuit breaker and for resetting the trip means, the trip means and the operating means being so related that the trip means will operate to release the circuit breaker irrespective of the position of the operating means and irrespective of any motion that the operating means may be executing at the time the trip means operates so that the trip means is trip free and will operate no matter whether the operating means is forcibly held in closed position or is being moved from one position to another.

Further objects are to provide a circuit breaker which is so constructed that the circuit breaker cannot be closed until the trip means has moved I back to normal position, and in which the resetting of the trip means is accomplished by moving the operating means towards open position, such motion being followed by movement to closed position after the resetting of the trip means when it is desired to again close the circuit breaker after the occurrence of the predetermined condition. 1

Further objects are to provide a circuit breaker construction which may be installed within a transformer casing and may be mounted above or submerged in the oil in the transformer casing, if desired, and which may be arranged so that the thermostatic means responds solely to the heat generated by the current passing through the thermostatic means or to the combined action of the heat of the oil from the transformer as well as the heat due to current passing through the thermostatic means or which may be arranged to respond solely to the heat of the oil.

Further objects are to provide a circuit breaker which has a heavy contact pressure when it is closed, in which this heavy. contact pressure is maintained during the operation of the circuit breaker until the instant at which the contacts June 2, 1944, Serial No. 538,365. Divided and this application January 4, 1947, Serial No. 720,145

2 Claims. (Cl. 200-116) are suddenly separated, thereby avoiding burning of the contacts under overload conditions.

Further objects are to provide a circuit breaker in which the trip means is required to exert only a very small force in order to cause automatic operation, the relation of the parts insuring relatching without any chance oiwedging or jamming either the trip mechanism as a whole or any portion of the latch means.

Further objects are to provide a circuit breaker which has switch operating means adapted to selectively pivot about either of two different movable pivots, the pivotal motion occurring about the first pivot due to the motion of the second pivot when the circuit breaker is automatically actuated and occurring about the second pivot when the circuit breaker is manually operated, the second pivot after automatic operation being restored to its initial position when the circuit breaker is manually reset.

Further objects are to provide a circuit breaker which is so made that it has a quick opening and quick closing motion when it is manually or automatically opened or when it is manually closed, respectively, which has spring actuated quick acting means so arranged that the quick acting means is adapted to rock over dead center, when manually operated, and is mechanically assisted in this motion at approximately the instant that it is passing dead center, and which is so constructed that although the spring means may break, nevertheless the circuit breaker may be positively manually opened independently of any spring action, thus providing additional security in the operation of the circuit breaker.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a sectional elevation of the circuit breaker, such view corresponding to a section on the line l-l of Figure 2, and showing the circuit breaker in closed position.

Figure 2 is a sectional view on the line 2-,-2 of Figure 1 and on the line 2-2 of Figure 3.

Figure 3 is a sectional view on the line 3-3 of Figure 2.

Figure 4 is a sectional view on the line 4-4 of Figure 3.

Figure 5 is a sectional view on the line 5-5 of Figure 3.

Figure 6 is a sectional view corresponding to Figure 3 with some of the parts shown in full, such view showing the circuit breaker in manually open position.

Figure 7 is a view corresponding to Figure 3 showing some of the parts in full and showing 3 the circuit breaker in automatically tripped position.

Figure 8 is a top plan view with the cover removed and with parts broken away.

Figure 9 is fragmentary view showing the circuit breaker mounted in a transformer casing.

Figure 10 is a view taken on the line Ill-Ill of Figure 9.

Figure 11 shows the circuit breaker positioned in a casing for wall mounting.

Figure 12 is a wiring diagram.

The circuit breaker comprises a base portion I formed of insulating material and provided with a raised, centrally located portion 2 which has an upwardly extending, integral projecting part or stop member 3. A top portion 4 is also formed of insulating material and is spaced upwardly from the base portion. The top is provided with a pair of downwardly extending integral leg portions 5 which fit within recesses 6 formed in the base. The legs 5 are joined by an integral transverse web or bar 1. A cover 8 is provided above the top portion 4 and is suitably seated in a flanged marginal portion of the top 4 as shown. A metalcasing or housing 9 is positioned between the top and bottom portions and is seated in grooves formed in such portions. The cover, top and bottom portions are held together by means of a pair of front tie rods l and a rear tie rod II. g

It will be seen that the construction provides a relatively large housed portion between the base I and the top 4 within which substantially all of the operating mechanism is positioned and that the space between the cover 8 and the top 4 provides a housed space within which the thermostatic members or condition responsive means is positioned.

The circuit breaker chosen for illustration is a two pole circuit breaker provided with a pair of stationary contacts 12 which are connected to the line terminals II. The movablecontacts are indicated at I 4 and are in the form of plugshaped members secured to rigid arms l5, see Fi ure 1. The movable contacts are each carried by a channel-shaped metal member I 8 and are freely slidable through the rear wallof such member. Each movable contact i 4 is urged outwardly by a spring 11. The metal channelshaped members 16 loosely house the rigid arms 15. The metal channel members It are rigidly se ured to a rock shaft indicated generally at l8. Th s rock shaft, as shown most clearly in Figure 3. is provided with a rectangular metal center member l9 which is encased in a rectangular insu ating sheath 20. The rigid arms I are con ec ed to flexible leads or conductors 2| which extend upwardly on opposite sides of the device and are connected to connecting portions 22 in turn electrically connected to the right and left-hand pair of thermostatic members, as may be seen from Figures 1 and 8.

Each pair of thermostatic means comprises an outer thermostatic member 23 adapted to control a light switch and an inner thermostatic member 24 adapted to control the circuit breaker. These thermostatic members are bimetal members and will be described in greater detail hereinafter. The thermostatic members 23 and 24 are individually anchored at their rear ends and adjacent their free ends are electrically joined by means of flexible connectors 25 to the load terminals 28, see Figure 8. This permits independent mechanical motion of the thermostatic members 23 and 24 although such members are electrically connected. The purpose of this will appear hereinafter,

Switch operating means in the form of a channel-shaped metal member 21 is rigidly secured to the shaft 18, as shown in Figures 3, 6, and 7. The switch operating means 21' is provided with elongated, longitudinally extending slots 28 in its side walls within which flanged rollers 28 are adapted to travel. The rollers 2! are carried by a transverse shaft 20. The shaft 20 is carried by an actuator formed of a pair of members 3| which are pivoted as indicated at 22 to a rigid channel-shaped frame 23. The frame 33 is car ried by the transverse web 1. The rollers 28 and the shaft 30 constitute the first pivot means and are adapted to rock the switch to open and closed position when the actuator is rocked about the pivot pins 22 in a manner hereinafter to appear. 1

The upper end of the switch operating means 21 has spaced arms which are provided with a second pivot means which consists oi shafts 34 upon which rollers 35 are mounted, see Figures 1, 4, and 7. The rollers 25 are adapted to travel in arcuate slots 36 formed in the rigid frame 33 and the shaft and rollers constitute the second pivot means for the switch operating member 21. Normally the second pivot means is held locked in its outermost position, that is to say, adjacent the right-hand end of the slot 36 as viewed in Figure l, by means of the main latch lever 31. This latch lever is provided with a pair of arms located on opposite sides of the rigid frame 33 and pivoted as indicated at 38 to such frame. The arms are joined by means of a transverse web 39 provided with cut out portions 40, see Figure 4.

Biasing means are provided which bias the second pivot-means 34. 35 to the left as viewed in Figures 4 and 7. This biasing means consists of a compression spring 4| which bears at opposite ends against U-shaped bail like members 42 and 43. The bail like member 42 is loosely pivoted on the pins II and the bail like member 43 is loosely pivoted on the pins 34. A flat bar 44 extends loosely through the spring and through the bail member 43 and is secured to the bail member 42. However, as stated the second pivot means 34, 35 is prevented from moving to the left under normal conditions by means of the latch lever 31. Each of the arms of the latch lever is provided with a downwardly projecting portion 45, see Figure 1, which is provided with a face 46 which has a slight slant, as may be seen from Figure 1 so that it acts like a cam and tends to bias the latch lever 31 towards clockwise or unlatching motion. It is also to be noted that the latch lever, due to the fact that its right-hand portion is heavier than its left-hand portion, is also biased towards clockwise motion by means of gravity.

The latch lever is normally prevented from moving to releasing position by means of a latch bar 41 pivoted intermediate its ends by means of the headed screw member 48 to the web 3! of the latch lever, as shown most clearly in Figure 2.

.The latch bar 41 is provided with a pair of outwardly projecting end portions 49 which are engaged by downwardly projecting fingers 50 of a spring 51 loosely coiled about the member 48.

The parts are so arranged, as may be seen from Figures 2, 3, and 4, that the fingers 50 bear against the front face of the web 39 of the main latch lever and thus normally hold the latch bar 41 in a definitepredetermined position transversely of the main latch lever 31. Auxiliary latch members 52 are loosely mounted on a pivot pin 53 and are preferably rigid with sleeves 53', see Figure 2, to provide adequate bearing surface on the pin. The auxiliary latch members 52 are provided with fiat faces 54 which normally engage beneath the projecting portions 49 of the latch bar, see Figure 3. These auxiliary latches .or latch members 52 are urged in a counterclockwise direction by means of springs 55. They are normally prevented from rotation by means of shouldered portions 56 formed thereon and respectively engaging circular pads or members 51 rigidwith threaded stems 58, which stems are threaded through insulating blocks 59 rigidly carried by the outer or free ends of the inner thermostatic members 24. Adjusting knobs 60 are carried by each of the threaded stems 58 but are not threaded thereon. Nuts GI and washers 82 are also carried by the threaded stems 58 and springs 63 bear against the nuts and against washers 64 which in turn rest upon fittings 65 carried by the insulating blocks 59, see Figure 3. The fittings 65 are each provided with an upturned finger 68 which is adapted to be engaged by the upturned finger 61 to thereby limit the extent of rotation of the adjusting knob 69.

It is to be noted that bimetal thermostatic members vary due to differences in material and in the process followed in their manufacture. Wide variations are taken care of by properly adjusting the threaded stems 58, it being noted that the upper end of the stems are slotted to receive a screw driver. After proper adjustment has been obtained, the knobs 60 are soldered or otherwise secured to the threaded shanks 58. Thereafter a certain range of adjustment is permitted as the knobs 60 may be rotated approximately a full revolution. In other words, the range through which the thermostatic members are to work is determined by the rough adjustment of the stems 58 in the insulating members 59 by means of a screw driver, as previously described, and within this range the exact adjustment at which the thermostatic members are adapted to release the trip means is determined by the adjustment of the knobs 60.

The pin 53 may be carried by upturned arms 68 integral with a plate 89 secured to the top portion 4. The plate 69 is provided with projecting fingers which are adapted to be engaged. by the extensions H of the auxiliary latches 52 to thus limit their counterclockwise motion.

It is to be noted that each of the auxiliary latches 52 is provided with a cam like extension .or finger 12 which constitutes a tripping element. The purpose of these fingers 12 will be apparent when the operation OI one of the thermostatic members 24 is considered. Suppose, for example, that one of the thermostatic members 24 operates and releases its auxiliary latch 52. This latch will execute a counterclockwise motion and in so doing the fingers or tripping element 12 will strike the corresponding finger 49 of the latch bar and will positively rock the latch bar and cause disengagement of the other end of the latch barfrom the other auxiliary latch 52, thus releasing the main latch lever 3]. If both thermostatic members 24 release their auxiliary latches 52 simultaneously, it will be seen that both auxiliary latches move away from the transversely extending latch bar and disengage the respective ends 49 thereof and allow the main latch lever 31 to move to releasing position.

when one or both of the thermostatic members or condition responsive members 24 releases its corresponding auxiliary latch lever or auxiliary latch element 52, the main latch lever or main latch element 3'? will rock in a clockwise direction due to the fact that it is biased by gravity towards this motion as its right-hand end is considerably longer than its left-hand end. However it is more heavily biased towards this releasing motion due to the fact that the latching face 46, see Figure 1, is in reality a cam face and the pressure of the second pivot means 34, 35 against such face tends to cause clockwise or releasing rocking motion of the main latch lever 31. When the main latch lever 31 releases the second pivot means 34, 35, the 'switch operating means 21- pivots about the first pivot means 29, 30 as it is biased towards counterclockwise motion by means of the spring 4! and the switch operating means and movable contacts l4 move from the position shown in Figures 1 and 3 to the position shown in Figure 7.

Main operating means are provided for operating the switch and for resetting the automatic tripping means. This main operating means comprising a U-shaped, bail like member I3 which is pivoted as indicated at 14 on opposite sides of the stationary frame 33. The main operating member I3 may be rocked from the position shown in Figures 1 and 3 to that shown in Figure 6 in any suitable manner, as by means of connecting links 15 pivotally connected by means of a transverse pin 16 with the main operating means 1'3 at their outer ends and at their inner ends pivoted to a crank 11 rigidly mounted on a tranverse rock shaft 18 carried in suitable supports and extending laterally through one side of the housing 9 as shown in Figure 5.

The rock shaft 18 may be operated in any suitable manner as by means of a handle 19 located externally of a transformer casing 80, the circuit breaker being preferably carried by the transformer indicated generally by the reference character BI and mounted below the level 82 of the oil within the casing, see Figure 9. Obviously the rock shaft 18 could be operated in any other manner desired, as by means of cranks and link mechanism from a rock shaft mounted above the oil level if desired: If the outwardly projecting extension 83 of the rock shaft is below the oil level 82, a suitable packing is provided to prevent loss of oil.

The main operating means 13 is connected by means of a pair of springs 84 with the first pivot means 29, 30. Preferably fittings 85 and 86 are provided for the outer ends of the springs 84. These fittings are seated within grooves formed in the pins or shafts l6 and 30, see Figure 3. The fitting 85 is mounted between the flanged rollers 29. It is also preferable to provide collars 88 On the shaft 18 to prevent shifting of such main operating shaft.

The main operating member 13 is provided with pins 89 which project inwardly from opposite sides and which are adapted to operate within slots 90 formed in opposite sides of the frame 33. These pins project into cut out portions 8| in the actuator formed of the members 3!. It is to be noted that the cut out portions 9! in the actuators 3| are so shaped that shoulders 92 are provided, see Figure 3. The purpose of these shoulders will appear from the following description of the manual operation of the apparatus.

Assume that the circuit breaker is in closed position and it is desired to manually open it. This is accomplished by rocking the rock shaft 18 and thereby moving the main operating means 13 from the position shown in Figures 1 and 3 to the position shown in Figure 6. During this rocking motion the line of pull of the springs 84 will pass'across the pivot means 32 of the actuator composed of the members 3I and will cause the actuator to suddenly rock in a clockwise direction to the position shown in Figure 6, thereby suddenly opening the circuit breaker. Obviously closing motion is accomplished by moving the main operating means from the position shown in Figure 6 to the position shown in Figure 3, the closing motion of the circuit breaker being very quick in view of the fact that the line of pull of the springs again crosses the pivot 32 of the actuator in passing from the position shown in Figure 6 to that shown in Figure 3. The shoulders 92 on the members 3| constituting the actuator, see Figure 3, have a double function. One of the functions is to start motion of the actuator at approximately the instant that the line of pull of the springs 84 is crossing the pivot point of the actuator when the main operating means 13 is being moved from the position shown in Figure 3 to that shown in Figure 6. The other purpose of the shoulders 92 is to insure opening of the circuit breaker by positive engagement between the pins 89 and the shoulders 92 even.

though the springs 84 should break, thus providing this additional safety feature.

The resetting after automatic trip ing is accomplished by moving the main ooerating means 13 from the position shown in Figure 7 to the position shown in Figure 6. Prior to the time that the main operating means 13 arrives at the position shown in Figure 6, it will be noted that the line of pull of the springs 54 passes across the pivot point of the actuator and consequently pulls the upper end of the switch operating means 21 to the right as viewed in Figure 6, thus compressing the spring H as the springs 84 exert a greater force than the spring 4| It is to be noted that the projecting portion 3 which extends upwardly from the base I is engaged by the transverse insulated shaft I8 of the switch operating means 21 during this resetting operation and consequently the switch operating means 21 pivots about the point of engagement between the shaft I8 and the projection 3. As the main operating means 13 continues upwardly to the position shown in Figure 6, it will engage the downwardly projecting portions 93 of the main latch lever ;31 and will rock such main latch lever to the position shown in Figure 6, the second pivot means 34, 35 having been first positioned to the right of the hook-shaped left-hand end of the main latching lever 31.

It is to be noted also that the auxiliary latches 52 are also reset. If both of the auxiliary latch levers 52 have been released by simultaneous action of the thermostatic members 24, it will be noted that the latch bar 41 will move upwardly and will simultaneously engage the cam portions 12 of each of the auxiliary latch levers 52 and will rock such latch levers to the position shown in Figure 6. During this motion, assuming that the thermostatic members 24 have cooled, the cam like portion 94 of the auxiliary levers will ride beneath the stops or pads 51 and will slightly raise the pads until the latching faces 56 of the auxiliary latch levers 52 are to the right as viewed in Figure 6 of the members 51. Thereafter when the main operating means 13 is moved downwardly towards clomd position from the position shown-in Figure 6, the transverse latch bar will rest upon the fiat portions or hook portions 54 of the auxiliary latch levers 52.

If only one of the thermostatic members 24 had operated, its auxiliary latch lever 52 would be released but the other latch lever would still be held by its thermostatic member 24. Under these conditions when the main latch lever 31 is rocked from the position shown in Figure 1 to that shown in Figure 6 during resetting, the appropriate end 45 of the latch bar will first engage the cam portion 12 of the released auxiliary latch lever 52 and its opposite end 40 will be rocked inwardly and will thus clear the hook portion and are connected together. Each signal switch member comprises a stationary contact member and a movable contact member 95 normally spring urged towards open position as shown in Figure 1. These signal switches are connected in parallel as is obvious and in series with a signal lamp or other signal means indicated by the ref erence character 01 in Figures 9 and 12. This signal lamp may be supplied from either secondary winding 50 of the transformer 39, see Figure 12, or may be, in the preferred form, supplied from a separate secondary III of the transformer 90. The signal switch means are controlled by the outer thermostatic members 23, see Figures 1 and 8. These thermostatic members are provided with insulating blocks III at their free ends through which threaded stems I02 pass. These stems are provided with pads or stop members I03 and with adjusting knobs I44 of identically the same construction as those previously described and initially set and subsequently accurately adjusted in exactly the same manner as that previously described.

The independence of the adjustment of the members 50 and I04 and such other associated parts relating thereto form the subject matter of the copending application of Alwin G. Steinmayer for Switch constructions, Serial No. 536,335 filed May 19, 1944, and which has issued as Patent No. 2,468,645, dated April 26, 1949.

Each thermostatic member 23 controls a signal switch operating means I05 which is mounted opposite the movable contact 96 of the signal switch and which is urged by means of a spring I00 in a counterclockwise direction towards signal switch closing motion. It is normally restrained by the engagement of the shoulder I01 of the signal switch operating means I05 with the stop or pad I03 of the thermostatic member. When the thermostatic member releases the signal switch operating means I05, such signal switch operating means closes its signal switch. The signal switch operating means I05 is provided with a cam face I00 so that the cam face will ride beneath and raise the pad or stop I03 when the signal switch operating means I05 is reset.

Each signal switch operating means I05 is pivotally mounted upon a fixedly positioned pin I09 carried by the stationary arms of a bracket H secured to the top 4. Preferably sleeves IE9 have their ends riveted to the members 105 to provide extensive bearing surface On thepins I99. The signal switch operating means 195 are provided with projecting pins H i which are adapted to be engaged by the upper ends of resetting levers I I2 pivotally supported on the shaft H3 which in turn is supported from the base I, see Figures 1 and 2. Preferably tubular members or sleeves H4 are riveted as indicated at H5 to the resettin levers H2 so as to provide the resetting levers with elongated bearings which are supported by the shaft H3.

The levers H2 are provided with cam portions H6 adapted to be engaged by the transverse pin 16 of the main operating means 13 when such main operating means is rocked upwardly. The cam portions H6 of the resetting levers H2 are so positioned that resetting takes place when the main operating means 13 is moved towards switch open position but prior to the opening of the circuit breaker so that it is possible, if it becomes desirable, to open the signal switch means by resetting the signal switch operating means without opening the circuit breaker.

- The adjustment of the threaded stems 58 and I02, see Figures 1 and 3, which are supported irom the thermostatic members 24 and 23 respectively, is such that any desired spread between current values required to operate the respective thermostatic members may be obtained '50 that the signal switch means will be closed for a current value and time interval less than that for which the circuit breaker will be opened.

The circuit breaker may be adapted for wall mounting as indicated in Figure 11 and may be completely housed as indicated at 8 and may be provided with an external lever or arm 19 for operating such circuit breaker. The signal lamp or other signal means, not shown in Figure 11, may be mounted either on the casing of the circuit breaker or at any desired point.

Referring to the wiring diagram of Figure 12, it will be seen that the primary of the transformer is indicated by the reference character H1 and that the secondary has a. grounded neutral in the particular form chosen for illustration. It is obvious that either a single pole circuit breaker could be used where a single secondary is employed or a two pole circuit breaker could be used for the three wire grounded neutral system shown in Figure 12, or any number of poles could be provided by suitably extending the shaft l8, see Figure 1, and providing it with the necessary number of movable contacts I4 and providing a corresponding number of stationary contacts [2.

It will be seen that a circuit breaker has been provided which has a quick closing motion when it is manually closed and which has a quick opening motion when it is either manually or automatically opened. It will be seen that the circuit breaker has heavy contact pressure though it may be easily operated either automatically or manually.

It will be seenfurther that relatively simple means are provided'ior automatically releasing the circuit breaker on overload and that the manual means is so arranged in collaboration with the automatic release means so as to reset the release means after automatic release when the manual means is moved towards switch open position without danger of jamming any of the parts.

It will be seen further that the switch operating means is so arranged that it is adapted to pivot about either of two pivot means so that when it is manually operated, it pivots about one of the pivot means and when it is automatically actuated, it pivots about the other of the pivot means.

It will be seen further that the circuit breaker is trip free and will release itself no matter whether the main operating means is forcibly held in switch closed position or is moving from one position to another position.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. In a circuit breaker having two switch means, a switch operating means for simultaneously operating both said switch means to open and close two electric lines, a pair of electrical overload means, a pair of auxiliary latch elements respectively controlled by said overload means, spring means for causing opening of said two switch means, a main latch element, and a latch bar controlling the action of said spring means through the agency of said main latch element and normally engaged and restrained by each auxiliary latch element, said pair of electrical overload means being respectively connected in said lines for causing disengagement of said auxiliary latch elements from said latch bar to release said spring means.

2. In a circuit breaker having two switch means,

a switch operating means for simultaneously operating both said switch means to open and close two electric lines, a pair of electrical overload means, a pair of auxiliary latch elements respectively controlled by said overload means, spring means for causing opening of said two switch means, a main latch element, and a latch bar controlling the action of said spring means through the agency of said main latch element and normally engaged and restrained by each auxiliary latch element, said pair of electrical overload means being respectively connected in said lines for causing disengagement of said auxiliary latch elements from said latch bar to release said spring means, said latch bar being pivoted intermediate its ends and each auxiliary latch element having a portion efiective when such auxiliary latch element is tripped to positively rock said latch bar and cause its disengagement from the other auxiliary latch element.

EDWIN A. LINK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,869,563v Jennings Aug. 2, 1932 1,955,327 Dorfman Apr. 17, 1934 2,185,524 Sachs Jan. 2, 1940 

